A British-Iranian charity worker has reportedly been in jail in Iran for more than a month, after being detained at Tehran airport on April 3 by Iran’s Islamic Revolutionary Guards Corps (IRGC). Nazanin Zaghari-Ratcliff, 37, was trying to return to her home in London, when she was arrested without charge, according to her family. The British passport of her 22-month-old daughter was also confiscated and she remained with her grandparents in Iran. Zaghari-Ratcliff has been transferred to an unknown location in Kerman Province, where she is said to be being held in solidarity confinement.

Zaghari-Ratcliff’s family say her interrogations relate to “national security,” Radio Free Europe reports. A change.org petition, aimed at British prime minister David Cameron, reports that Zaghari-Ratcliff has been denied access to a lawyer and has not been able to call her British husband, Richard.

“It is hard to understand how a young mother and her small child on holiday could be considered an issue of national security,” Richard Ratcliff said. “She has been over to visit her family regularly since making Britain her home.”

Zaghari-Ratcliff works for the Thomson-Reuters Foundation, which does not conduct any projects in Iran.